The influence of helmet size and shape on peak linear decelerations when impacting crash pads

AbstractDuring training and competition in short track speed skating, skaters commonly fall on the ice and slide into crash pads that line the boards of the rink. Skaters wear helmets to protect their heads from such impacts. Nevertheless, concussion injuries are not uncommon, especially from impacts into the crash pads. Basic mechanical principles suggest that, all other things being equal, smaller sized and rounder shaped helmets should reduce peak impact forces when hitting relatively soft crash pads. This study validates these assumptions and determines the magnitude of these effects using drop tests and a 3D accelerometer. Hemispherical head forms of various radii, each weighing approx. 4.5kg, were dropped from four heights (0.3-4.0 m) onto a crash pad. Peak linear decelerations were recorded. In one set of tests, complete hemispheres were used, highlighting the effect of helmet size (radius). In a second set of tests, another set of hemispheres of various radii were sliced to produce caps each with a diameter of 8” but each with a different radius of curvature. Impact tests at four drop heights using these caps revealed the effect of helmet shape. Size was found to be more important than shape, with the greatest effects being in the 10-20cm radius range, a range which is relevant to helmets used in the sport today

Rx Activité physique : Développement et implantation d’objectifs d’apprentissage en matière de counseling et de prescription d’activité physique dans les cursus des facultés de médecine canadiennes

Physical activity is an important component of health and well-being, and is effective in the prevention, management, and treatment of numerous non-communicable chronic diseases. Despite the known health benefits of physical activity in all populations, most Canadians do not meet physical activity recommendations. Physicians play a key role in assessing, counselling, and prescribing physical activity. Unfortunately, many barriers, including the lack of adequate education and training, prevent physicians from promoting this essential health behaviour. To support Canadian medical schools in physical activity curriculum development, a team of researchers, physicians, and exercise physiologists collaborated to develop a key set of learning objectives deemed essential to physican education in physical activity counselling and prescription. This commentary will review the newly developed Canadian Physical Activity Counselling Learning Objectives and give case examples of three Canadian medical schools that have implemented these learning objectives.L’activité physique est une composante importante de la santé et du bien-être, et elle est efficace dans la prévention, la prise en charge et le traitement de nombreuses maladies chroniques non transmissibles. Malgré les bienfaits qu’on lui reconnaît pour la santé des populations, la plupart des Canadiens ne suivent pas les recommandations en matière d’exercice. Les médecins jouent un rôle clé dans l’évaluation, le counseling et la prescription de l’activité physique, mais de nombreux obstacles, dont le manque de formation adéquate, les empêchent de promouvoir cette habitude de vie essentielle pour la santé. Afin d’aider les facultés de médecine canadiennes dans l’élaboration de leur cursus sur l’activité physique, une équipe composée de chercheurs, de médecins et de physiologistes de l’exercice a collaboré à la définition d’un ensemble d’objectifs d’apprentissage jugés indispensables à la formation des médecins pour qu’ils puissent offrir des conseils sur l’activité physique et la prescrire. Ce commentaire passe en revue les nouveaux objectifs d’apprentissage en matière de counseling en activité physique et donne des exemples de cas de trois facultés de médecine canadiennes qui ont mis en œuvre ces objectifs d’apprentissage

Life cycle assessment for three ventilation methods

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.A sustainable ventilation method is one of the possible solutions to mitigate climate change and carbon emission. This method shall involve an analysis of the environmental impact, energy performance, and economical cost-effectiveness. There are still few studies concerning the life cycle assessment (LCA) of various alternative ventilation systems incorporating the combined effect of life cycle cost (LCC) and carbon emission in the supply-and-installation phase, as well as energy performances in the operation phase. The supply-and-installation phase of the system materials and components has a significant contribution to the total energy consumption and environmental loads of buildings. This paper covers a systematic approach to estimate their environmental impact, which was counted in terms of energy demand and CO2 emission in the two phases. This approach has been applied to an actual typical classroom served by mixing ventilation (MV), displacement ventilation (DV) and stratum ventilation (SV). The results show that SV has the least environmental impact and life cycle cost (LCC). Results of this analysis demonstrated that by adopting DV and SV, it is possible to reduce the CO2 emission up to 23.25% and 31.71% respectively; and to reduce the LCC up to 15.52% and 23.89% respectively, in comparison with an MV system for 20 service years. This approach may be generally applied to a sustainability analysis of ventilation methods in various scales of air-conditioned spaces

Application of the Electrochemical Permeation Method for Hydrogen Diffusion Coefficient Determination in Pipeline Steel 10G2

In this article, we conduct research on the effect of corrosion tests on the hydrogen diffusion process in gas steel in electrochemical permeability tests. This tests show that a long corrosion test time reduces the hydrogen diffusion coefficient by an order of magnitude, indicating the formation of aging defects in the steel. During operation, the diffusion coefficient decreases by two orders of magnitude, which also indicates the formation of a large number of defects in the steel. Consequently, based on the change in the diffusion coefficient in the material, it is possible to assess the degree of material failure

Recommendations for Epstein-Barr virus–based screening for nasopharyngeal cancer in high- and intermediate-risk regions

A meeting of experts was held in November 2021 to review and discuss available data on performance of Epstein-Barr virus (EBV)–based approaches to screen for early stage nasopharyngeal carcinoma (NPC) and methods for the investigation and management of screen-positive individuals. Serum EBV antibody and plasma EBV DNA testing methods were considered. Both approaches were found to have favorable performance characteristics and to be cost-effective in high-risk populations. In addition to endoscopy, use of magnetic resonance imaging (MRI) to investigate screen-positive individuals was found to increase the sensitivity of NPC detection with minimal impact on cost-effectiveness of the screening program

Quorum-sensing

The agr quorum-sensing system links Staphylococcus aureus metabolism to virulence, in part by increasing bacterial survival during exposure to lethal concentrations of H2O2, a crucial host defense against S. aureus. We now report that protection by agr surprisingly extends beyond post-exponential growth to the exit from stationary phase when the agr system is no longer turned on. Thus, agr can be considered a constitutive protective factor. Deletion of agr resulted in decreased ATP levels and growth, despite increased rates of respiration or fermentation at appropriate oxygen tensions, suggesting that Δagr cells undergo a shift towards a hyperactive metabolic state in response to diminished metabolic efficiency. As expected from increased respiratory gene expression, reactive oxygen species (ROS) accumulated more in the agr mutant than in wild-type cells, thereby explaining elevated susceptibility of Δagr strains to lethal H2O2 doses. Increased survival of wild-type agr cells during H2O2 exposure required sodA, which detoxifies superoxide. Additionally, pretreatment of S. aureus with respiration-reducing menadione protected Δagr cells from killing by H2O2. Thus, genetic deletion and pharmacologic experiments indicate that agr helps control endogenous ROS, thereby providing resilience against exogenous ROS. The long-lived \u27memory\u27 of agr-mediated protection, which is uncoupled from agr activation kinetics, increased hematogenous dissemination to certain tissues during sepsis in ROS-producing, wild-type mice but not ROS-deficient (Cybb-/-) mice. These results demonstrate the importance of protection that anticipates impending ROS-mediated immune attack. The ubiquity of quorum sensing suggests that it protects many bacterial species from oxidative damage

Effect of Deutetrabenazine on Chorea Among Patients With Huntington Disease A Randomized Clinical Trial

Importance Deutetrabenazine is a novel molecule containing deuterium, which attenuates CYP2D6 metabolism and increases active metabolite half-lives and may therefore lead to stable systemic exposure while preserving key pharmacological activity. Objective To evaluate efficacy and safety of deutetrabenazine treatment to control chorea associated with Huntington disease. Design, Setting, and Participants Ninety ambulatory adults diagnosed with manifest Huntington disease and a baseline total maximal chorea score of 8 or higher (range, 0-28; lower score indicates less chorea) were enrolled from August 2013 to August 2014 and randomized to receive deutetrabenazine (n = 45) or placebo (n = 45) in a double-blind fashion at 34 Huntington Study Group sites. Interventions Deutetrabenazine or placebo was titrated to optimal dose level over 8 weeks and maintained for 4 weeks, followed by a 1-week washout. Main Outcomes and Measures Primary end point was the total maximal chorea score change from baseline (the average of values from the screening and day-0 visits) to maintenance therapy (the average of values from the week 9 and 12 visits) obtained by in-person visits. This study was designed to detect a 2.7-unit treatment difference in scores. The secondary end points, assessed hierarchically, were the proportion of patients who achieved treatment success on the Patient Global Impression of Change (PGIC) and on the Clinical Global Impression of Change (CGIC), the change in 36-Item Short Form– physical functioning subscale score (SF-36), and the change in the Berg Balance Test. Results Ninety patients with Huntington disease (mean age, 53.7 years; 40 women [44.4%]) were enrolled. In the deutetrabenazine group, the mean total maximal chorea scores improved from 12.1 (95% CI, 11.2-12.9) to 7.7 (95% CI, 6.5-8.9), whereas in the placebo group, scores improved from 13.2 (95% CI, 12.2-14.3) to 11.3 (95% CI, 10.0-12.5); the mean between-group difference was –2.5 units (95% CI, –3.7 to –1.3) (P < .001). Treatment success, as measured by the PGIC, occurred in 23 patients (51%) in the deutetrabenazine group vs 9 (20%) in the placebo group (P = .002). As measured by the CGIC, treatment success occurred in 19 patients (42%) in the deutetrabenazine group vs 6 (13%) in the placebo group (P = .002). In the deutetrabenazine group, the mean SF-36 physical functioning subscale scores decreased from 47.5 (95% CI, 44.3-50.8) to 47.4 (44.3-50.5), whereas in the placebo group, scores decreased from 43.2 (95% CI, 40.2-46.3) to 39.9 (95% CI, 36.2-43.6), for a treatment benefit of 4.3 (95% CI, 0.4 to 8.3) (P = .03). There was no difference between groups (mean difference of 1.0 unit; 95% CI, –0.3 to 2.3; P = .14), for improvement in the Berg Balance Test, which improved by 2.2 units (95% CI, 1.3-3.1) in the deutetrabenazine group and by 1.3 units (95% CI, 0.4-2.2) in the placebo group. Adverse event rates were similar for deutetrabenazine and placebo, including depression, anxiety, and akathisia. Conclusions and Relevance Among patients with chorea associated with Huntington disease, the use of deutetrabenazine compared with placebo resulted in improved motor signs at 12 weeks. Further research is needed to assess the clinical importance of the effect size and to determine longer-term efficacy and safety